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authorManuel Novoa III <mjn3@codepoet.org>2004-01-02 08:44:58 +0000
committerManuel Novoa III <mjn3@codepoet.org>2004-01-02 08:44:58 +0000
commit400e6fc264cbe6ca3ca572d94bbf5f929f256713 (patch)
tree7c7cd0d0dc3e59fe1ab7e369e73c1d521797c47b /libc/unistd/exec.c
parent33e58d3c9e1282b210313c8ee46daeb74edb99e8 (diff)
Redo the exec functions to comply with SUSv3.
Diffstat (limited to 'libc/unistd/exec.c')
-rw-r--r--libc/unistd/exec.c319
1 files changed, 319 insertions, 0 deletions
diff --git a/libc/unistd/exec.c b/libc/unistd/exec.c
new file mode 100644
index 000000000..fa1eda2b9
--- /dev/null
+++ b/libc/unistd/exec.c
@@ -0,0 +1,319 @@
+/* Copyright (C) 2004 Manuel Novoa III
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the Free
+ * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+/* Jan 1, 2004
+ * Initial version of a SUSv3 compliant exec*() functions.
+ */
+
+/* NOTE: Strictly speaking, there could be problems from accessing
+ * __environ in multithreaded programs. The only way around this
+ * that I see is to essentially lock __environ access (modifying
+ * the setenv code), make a copy of the environment table (just the
+ * pointers since the strings themselves are never freed), and then
+ * unlock prior to the execve call. If that fails, then we'd need
+ * to free the storage allocated for the copy. Better ideas anyone?
+ */
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <stdarg.h>
+#include <limits.h>
+#include <unistd.h>
+#include <sys/mman.h>
+
+extern char *__strchrnul(const char *s, int c);
+
+/**********************************************************************/
+#ifdef __UCLIBC_HAS_MMU__
+
+/* We have an MMU, so use alloca() to grab space for buffers and
+ * arg lists. */
+
+# define EXEC_ALLOC_SIZE(VAR) /* nothing to do */
+# define EXEC_ALLOC(SIZE,VAR) alloca((SIZE))
+# define EXEC_FREE(PTR,VAR) ((void)0)
+
+#else
+
+/* We do not have an MMU, so using alloca() is not an option.
+ * Less obviously, using malloc() is not an option either since
+ * malloc()ed memory can leak in a vfork() and exec*() situation.
+ * Therefore, we must use mmap() and unmap() directly.
+ */
+
+# define EXEC_ALLOC_SIZE(VAR) size_t VAR; /* Semicolon included! */
+# define EXEC_ALLOC(SIZE,VAR) __exec_alloc((VAR = (SIZE)))
+# define EXEC_FREE(PTR,VAR) __exec_free((PTR),(VAR))
+
+extern void *__exec_alloc(size_t size);
+extern void __exec_free(void *ptr, size_t size);
+
+#endif
+/**********************************************************************/
+#ifdef L___exec_alloc
+
+#ifndef __UCLIBC_HAS_MMU__
+
+void *__exec_alloc(size_t size)
+{
+ void *p;
+
+ p = mmap(0, size, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_ANONYMOUS, -1, 0);
+
+ return (p != MAP_FAILED) ? p : NULL;
+}
+
+void __exec_free(void *ptr, size_t size)
+{
+ if (ptr) {
+ munmap(ptr, size);
+ }
+}
+
+#endif
+
+#endif
+/**********************************************************************/
+#ifdef L_execl
+
+int execl(const char *path, const char *arg, ...)
+{
+ EXEC_ALLOC_SIZE(size) /* Do NOT add a semicolon! */
+ int n;
+ char **argv;
+ char **p;
+ va_list args;
+
+ n = 0;
+ va_start(args, arg);
+ do {
+ ++n;
+ } while (va_arg(args, char *));
+ va_end(args);
+
+ p = argv = (char **) EXEC_ALLOC((n+1) * sizeof(char *), size);
+
+ p[0] = (char *)arg;
+
+ va_start(args, arg);
+ do {
+ *++p = va_arg(args, char *);
+ } while (--n);
+ va_end(args);
+
+ n = execve(path, (char *const *) argv, __environ);
+
+ EXEC_FREE(argv, size);
+
+ return n;
+}
+
+#endif
+/**********************************************************************/
+#ifdef L_execv
+
+int execv(__const char *path, char *__const argv[])
+{
+ return execve(path, argv, __environ);
+}
+
+#endif
+/**********************************************************************/
+#ifdef L_execle
+
+int execle(const char *path, const char *arg, ...)
+{
+ EXEC_ALLOC_SIZE(size) /* Do NOT add a semicolon! */
+ int n;
+ char **argv;
+ char **p;
+ char *const *envp;
+ va_list args;
+
+ n = 0;
+ va_start(args, arg);
+ do {
+ ++n;
+ } while (va_arg(args, char *));
+ envp = va_arg(args, char *const *); /* Varies from execl and execlp. */
+ va_end(args);
+
+ p = argv = (char **) EXEC_ALLOC((n+1) * sizeof(char *), size);
+
+ p[0] = (char *)arg;
+
+ va_start(args, arg);
+ do {
+ *++p = va_arg(args, char *);
+ } while (--n);
+ va_end(args);
+
+ n = execve(path, (char *const *) argv, envp);
+
+ EXEC_FREE(argv, size);
+
+ return n;
+}
+
+#endif
+/**********************************************************************/
+#ifdef L_execlp
+
+int execlp(const char *file, const char *arg, ...)
+{
+ EXEC_ALLOC_SIZE(size) /* Do NOT add a semicolon! */
+ int n;
+ char **argv;
+ char **p;
+ va_list args;
+
+ n = 0;
+ va_start(args, arg);
+ do {
+ ++n;
+ } while (va_arg(args, char *));
+ va_end(args);
+
+ p = argv = (char **) EXEC_ALLOC((n+1) * sizeof(char *), size);
+
+ p[0] = (char *)arg;
+
+ va_start(args, arg);
+ do {
+ *++p = va_arg(args, char *);
+ } while (--n);
+ va_end(args);
+
+ n = execvp(file, (char *const *) argv);
+
+ EXEC_FREE(argv, size);
+
+ return n;
+}
+
+#endif
+/**********************************************************************/
+#ifdef L_execvp
+
+/* Use a default path that matches glibc behavior, since SUSv3 says
+ * this is implementation-defined. The default is current working dir,
+ * /bin, and then /usr/bin. */
+static const char default_path[] = ":/bin:/usr/bin";
+
+int execvp(const char *path, char *const argv[])
+{
+ char *buf = NULL;
+ char *p;
+ char *e;
+ char *s0;
+ char *s;
+ EXEC_ALLOC_SIZE(size = 0) /* Do NOT add a semicolon! */
+ size_t len;
+ size_t plen;
+
+ if (!path || !*path) { /* Comply with SUSv3. */
+ BAD:
+ __set_errno(ENOENT);
+ return -1;
+ }
+
+ if (strchr(path, '/')) {
+ execve(path, argv, __environ);
+ CHECK_ENOEXEC:
+ if (errno == ENOEXEC) {
+ char **nargv;
+ EXEC_ALLOC_SIZE(size2) /* Do NOT add a semicolon! */
+ size_t n;
+ /* Need the dimension - 1. We omit counting the trailing
+ * NULL but we actually omit the first entry. */
+ for (n=0 ; argv[n] ; n++) {}
+ nargv = (char **) EXEC_ALLOC((n+2) * sizeof(char *), size2);
+ nargv[0] = argv[0];
+ nargv[1] = (char *)path;
+ memcpy(nargv+2, argv+1, n*sizeof(char *));
+ execve("/bin/sh", nargv, __environ);
+ EXEC_FREE(nargv, size2);
+ }
+ } else {
+ if ((p = getenv("PATH")) != NULL) {
+ if (!*p) {
+ goto BAD;
+ }
+ } else {
+ p = (char *) default_path;
+ }
+
+ plen = strlen(path);
+ if (plen > (FILENAME_MAX - 1)) {
+ ALL_TOO_LONG:
+ __set_errno(ENAMETOOLONG);
+ return -1;
+ }
+ len = (FILENAME_MAX - 1) - plen;
+
+ if ((buf = EXEC_ALLOC(FILENAME_MAX, size)) != NULL) {
+ int seen_small = 0;
+ s0 = buf + len;
+ memcpy(s0, path, plen+1);
+
+ do {
+ s = s0;
+ e = __strchrnul(p, ':');
+ if (e > p) {
+ plen = e - p;
+ if (e[-1] != '/') {
+ ++plen;
+ }
+ if (plen > len) {
+ goto NEXT;
+ }
+ s -= plen;
+ memcpy(s, p, plen);
+ s[plen-1] = '/';
+ }
+
+ execve(s, argv, __environ);
+
+ seen_small = 1;
+
+ if (errno != ENOENT) {
+ path = s;
+ goto CHECK_ENOEXEC;
+ }
+
+ NEXT:
+ if (!*e) {
+ if (!seen_small) {
+ goto ALL_TOO_LONG;
+ }
+ break;
+ }
+ p = e + 1;
+ } while (1);
+ }
+ }
+
+ EXEC_FREE(buf, size);
+
+ return -1;
+}
+
+#endif
+/**********************************************************************/